diff --git a/slixmpp_omemo/__init__.py b/slixmpp_omemo/__init__.py
index 3c2f689..b31d238 100644
--- a/slixmpp_omemo/__init__.py
+++ b/slixmpp_omemo/__init__.py
@@ -538,7 +538,7 @@ class XEP_0384(BasePlugin):
         lengths = map(lambda d_l: d_l[1], receiving_chain_lengths)
         return max(lengths, default=0) > self.heartbeat_after
 
-    def make_heartbeat(self, jid: JID) -> Message:
+    async def make_heartbeat(self, jid: JID) -> Message:
         """
             Returns a heartbeat message.
 
@@ -548,7 +548,7 @@ class XEP_0384(BasePlugin):
         """
 
         msg = self.xmpp.make_message(mto=jid)
-        encrypted = self.encrypt_key_transport_message(
+        encrypted = await self.encrypt_key_transport_message(
             plaintext=None,
             recipients=[jid],
             expect_problems=None,
@@ -644,8 +644,10 @@ class XEP_0384(BasePlugin):
             asyncio.ensure_future(self._publish_bundle())
 
         if self.auto_heartbeat and self.should_heartbeat():
-            msg = self.make_heartbeat(jid)
-            msg.send()
+            async def send_heartbeat():
+                msg = await self.make_heartbeat(JID(jid))
+                msg.send()
+            asyncio.ensure_future(send_heartbeat())
 
         return body